A polycarbonate-polyorganosiloxane copolymer (hereinafter sometimes abbreviated as “PC-POS copolymer”) has been attracting attention because of its excellent properties, such as high impact resistance, chemical resistance, and flame retardancy. Accordingly, the polycarbonate-polyorganosiloxane copolymer has been expected to be widely utilized in various fields, such as the field of electrical and electronic equipment and the field of automobiles. In particular, the utilization of the polycarbonate-polyorganosiloxane copolymer in casings for a cellular phone, a mobile personal computer, a digital camera, a video camera, an electric tool, and the like, and in other commodities has been expanding.
In normal cases, a homopolycarbonate using 2,2-bis(4-hydroxyphenyl)propane [common name: bisphenol A] as a dihydric phenol serving as a raw material has been generally used as a typical polycarbonate. In order to improve the physical properties of the homopolycarbonate, such as flame retardancy and impact resistance, it has been known that a polycarbonate-based resin composition is obtained by mixing a polycarbonate-polyorganosiloxane copolymer using a polyorganosiloxane as a copolymerizable monomer in the homopolycarbonate (Patent Document 1).
As the content of a polyorganosiloxane block in the polycarbonate-polyorganosiloxane copolymer becomes larger, the resin composition containing a predetermined amount of the polyorganosiloxane block can be produced at a lower mixing ratio with respect to the homopolycarbonate. Accordingly, the time period for which the polycarbonate-polyorganosiloxane copolymer needed for obtaining the resin composition containing the predetermined amount of the polyorganosiloxane block is produced can be shortened.